Annotea originated metadata based, shared/social
bookmarks and topics as a logical extension to Annotea shared annotations and
replies. These bookmarks and topics precede the tagging and social
bookmarking services and tools existing today. Annotea bookmarks and topics
support ordinary users in Web tagging and recalling relevant information
while supporting the use of their own personal concepts (folksonomies). The
user concepts can be shared and linked to more standard concepts when users
learn about them. Like other Annotea objects, bookmarks and topics help
collaboration in the context of the Web documents, but also support other
user interfaces. The Semantic Web technologies support merging Annotea
objects from different sources and easily extending the bookmark and topic
information.

1. INTRODUCTION

Humans are meaning makers. They create concepts, make associations,
comment, clarify, annotate, review, organize, bookmark, tag and file into
categories often starting from personal concepts that are shared by different
groups when they become more developed. Annotea [16] lets ordinary users
create and collaboratively share familiar objects adding meaning to Web,
including annotations, discussions threads, bookmarks, and topics. Annotea
objects can be explored in the context of the Web resources they refer to but
they can also be used in many other innovative ways. Annotea bookmarks with
topics [10, 11, 14, 15] can be used for simple Web tagging and precede Web
tagging services, such as [8] but they can also offer other information and
support for various user needs.

Annotea gets its inspiration from observing users’ needs and problems and
explores user scenarios based on those observations [10]. It uses the
Semantic Web technologies for implementation the solutions but hides the
Semantic Web under familiar objects and user interfaces. Annotea defines a
basic annotation/bookmarking framework [9] with schemas for Annotea objects
[2, 4, 12] and server protocols [17]. In addition, sample user interfaces
illustrate how to utilize the framework, for instance, in Amaya
browser/editor [1] and in Annotea Ubimarks [5]. In addition, many other
clients have been developed outside the Annotea team. Semantic Web
technologies [7] support seamless merging of Annotea objects from different
sources and easy extensions of these objects.

Annotea shared or social bookmarks allow users to recall Web resources,
such as Web documents, services, music, images and blogs while storing
additional information about these resources. Annotea topics support user
defined simple concepts (tags). These can be used to form personal ontologies
(folksonomies). In Annotea the topics can be stored locally or shared with
user groups. The bookmarks and topics can be linked to standard concepts
gradually when the user has learned enough to make that connection instead of
forcing the users to learn standard ontologies before they can start
developing their ideas.

Commonly available shared bookmarks repositories can create a network
effect leading to many new discoveries. Annotea bookmarks and topics help
collaboration and finding relevant information even when users use different
concepts, which is often the case in cross disciplinary fields, such as life
science or usability/user experience or even in marketing or research where
users are awarded from finding original concepts instead of using the already
existing ones.

In addition to proving a simple tool for creating meaning, Annotea
bookmarks and topics can be used as user profiles, collected to repositories
and used with search engines and data mining applications. Annotea bookmarks
and topics can also contain information not just about the user but his or
her social network. Again, this can be used to support the finding of more
relevant information.

As shared bookmarks are easy to create we hope to be able to see network
effects in many applications using bookmark repositories, such as data mining
applications, services with user profiles, search engines and applications
organizing blog type information.

2. ANNOTEA ARCHITECTURE

Annotea [9, 16] has demonstrated the use of the Semantic Web based
annotations and replies that can be stored to different annotation servers.
Annotea shared bookmarks and topics are based on the same technology.

Figure 1 presents the basic Annotea architecture. Various RDF metadata
stores and services can store Annotea objects, such as the bookmarks and
topics we are mostly interested in the context of tagging. These objects have
URIs and properties.

Figure 1. The basic Annotea architecture.

Annotea protocol has been defined for the metadata stores based on HTTP.
With bookmarks and topics we also use normal HTTP, FTP, and possibly other
Web protocols to store them as Web documents.

Annotea user interfaces provide different views to the Annotea objects.
When these interfaces are attached to browsers users can seamlessly
collaborate via Annotea objects in the context of the Web documents or other
Web resources. In addition, Annotea objects can be used in many other kinds
of applications and user interfaces. For instance, they can form user defined
profiles for services or information repositories for selected domains that
can help order results from search agent in a more meaningful way [18].

3. BOOKMARK AND TOPIC OBJECTS

Figure 2. Bookmark and topic
hierarchy.

During the first phase of Annotea development many informal discussions
were performed with users and additional user scenarios were developed. The
need for categories was high on the users’ wish list, especially status
categories were needed to mark the processed annotations. During the second
phase, we selected to focus our scarce resources to broaden the scope and add
bookmark and topic objects. The goal was to make sure that our approach was
extensible and the different metaphors could work together. In addition, this
approach gave us a chance to experiment with some other ideas before going
back and improving the annotation implementations.

The shared bookmark metaphor with topics was perfect for Annotea as shared
bookmarks could easily be seen as a variation of annotations. Furthermore,
most users were not only familiar with bookmarks but had actually used
traditional bookmark implementations. In addition, traditional browser
bookmark user interfaces have a lot of enhancement possibilities that can
benefit from the Semantic Web approach. For instance, the user interface can
utilize the document context to remind the user that she has previously
bookmarked the page or let the user define, share and link to other users'
topics or categories. Furthermore, many other applications can utilize the
bookmark metadata if it becomes widely available.

Annotea topics allow users to create and maintain shared classifications
or informal categories [13]. A bookmark can be cataloged under one or more
topics and presented to the user in a topic hierarchy (see Figure 2).

Annotea bookmark and topic user interfaces also provide information in
document context. When a user browses pages she can see that someone has
bookmarked a page from the pagemark icon that opens up to show a list of
bookmarks. These bookmarks and their topics can be easily followed to find
information about related documents in the RDF stores the user is currently
subscribing.

Users collaborating in similar or related research areas can benefit from
the bookmark and topic information. They can see bookmarks on a current page
and find related topics and other bookmarks to possibly interesting documents
under these topics. For instance, in Figure 3 the user sees that the page
about Groucho Marx has been bookmarked by looking the “Pagemarks” icon on the
left side of the toolbar, opens the Bookmarks on page window sees two topics
“Actors” and “Writers”, and presses the bookmarks link related to “Writers”
to find other “Writers”.

Figure 3. Following the link chain
from bookmarks on this page to related topics and bookmarks.

As the Annotea topics are user generated they can support learning. During
the early phases of innovations and research the topics can be as vague as
needed. When more learning happens and standard concepts are discovered and
understood the user can refine his or her own topics and link them to
concepts in well established ontologies.

The Annotea topics can easily define concepts outside the conventional
categories, such as status (see Figure 4). If the topics are separated from
the bookmark stores the user can define which aspects she is interested in at
each moment by subscribing those topic hierarchies. Similarly, the presented
bookmark stores can be selected in a certain domain area or by the research
group depending on how they are organized. There are many possibilities for
enhancing this user interface.

4. EXTENDING ANNOTEA OBJECTS

Annotea usually stores some basic information about the bookmarks. For
instance who has created it and when it was created. Other information can
also be added. For instance, it is easy to use different descriptions of the
user. For instance, in Annotea Ubimarks we let the user to add a URI to his
or her social network information by using foaf:maker
when the user feels comfortable in using it (see Figure 5). This social
network information can be used as additional help when trying to find
related documents in some domain area. Similarly, other properties can be
easily added to the bookmark and topic objects as well.

5. MIXING METAPHORS

Figure 6.
Bookmarks and annotation concepts mix in the real world.

The Annotea objects, especially annotations and bookmarks, do not differ
very much from each other and can be easily thought as variations of the same
class. However, we have also had long and intense discussions with users
seeing annotations and bookmarks as a totally different concept and
explaining that it would be confusing if bookmarks were annotations. On the
other hand, we also have users who want to immediately extend the bookmarks
so that they can refer not only to a Web resource with a URI but also to a
part of a document in a similar way as annotations.

The Semantic Web metadata of the objects is easy to extend in different
ways but designing the user interface to be both simple and expressive enough
is critical. Our current view is to keep things simple and see what happens
when users start using these interfaces more. Our hope is to be able to
experiment in Mozilla with Annozilla [6], an Annotea client for annotations
and Ubimarks, an Annotea client for bookmarks and topics.

One solution would be to let users create annotations to point to parts of
the document and then bookmark that annotation to give it a category and make
it easy to find. This would match nicely the way the annotations and
bookmarks are combined in Figure 6 examining the real world usage of
annotations and bookmarks.

5. CONCLUSIONS

Annotea objects for shared/social bookmarks and topics provide ordinary
users familiar metaphors for Web tagging and creating folksonomies.
Furthermore, they let the users generate reusable and easily extendible
Semantic Web metadata without having to learn and understand more about the
Semantic Web.

Unlike many currently popular services Annotea framework let’s users have
a choice where to store the bookmarks and topics. Users subscribe the data
stores containing the various Annotea objects they are interested in at that
moment. Stores can be local files, global servers and or Web documents
containing the metadata. Web documents offer users an easy alternative to get
started without investing in installation of a server. They can also be used
to archive snapshots of the selected Annotea objects outside the server.

Furthermore Annotea object metadata generated by the users can be easily
combined and reused in many other applications, such as user profiles for
services, data mining and search engine applications, chatrooms, and
blogs.

For developers Annotea offers an easy and flexible interface for merging
metadata from several different sources and doing queries against it.
Different views to the data can be created easily, and it is easy to let the
users follow tracks of data from the information on the current page to
possibly related information. Extending the Semantic Web data in Annotea
objects is easy as well. Defining a simple user interface for extensions is
relatively easy, but adding more complex user interface definitions to the
extensions needs more research.

6. ACKNOWLEDGMENTS

Many people have contributed to Annotea and helped to make it what it is
today. I want to give special thanks to Jose Kahan, Eric Prud'hommeaux and
Ralph Swick.